Thermostatic control device for



Patented Dec. 12, 1950 UNITED STATES PATENT OFFICE THERMOSTATIC CONTROL DEVICE FOR GAS-BURNING APPLIANCES Application June 26, 1948, Serial No. 35,306

10 Claims. 1

This invention relates to control systems and, more particularly, to condition responsive controls for ower-driven apparatus, such as clothes dryers, and is a continuation-in-part of our copending application Serial No. 688,582 filed Au ust 5, 1942.

Appliances of the type indicated may include a motor-driven shell or drum in which the clothes are placed for tumbling, and a heating device from which heated air may be circulated by a fan or blower throughout the load of clothing which is undergoing the drying operation.

A gaseous fuel burner is employed as the heating device and is provided with an automatic pilot burner component for shutting off the main burner gas should the pilot burner flame become extinguished. A normal starting operation must then be conducted in order to place the appliance in full running condition.

An object of the present invention is to facilitate the starting operation.

Another object of the invention is to eliminate a separate igniting operation for the burner component.

Another object of the invention is to guard against the hazardous efiects of over temperature in the appliance.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawing, which is a schematic view of a clothes drying apparatus embodying the invention.

Referring more particularly to the drawing, the usual drum or shell in is shown as being subject to the heat of a flame of a main fuel burner [2 having a pilot burner l4 in lighting proximity thereto. The shell is of the power-driven type and an electric motor I6 is shown associated therewith for driving purposes. The motor l6, may, in addition, drive the usual fan or blower (not shown) for circulating the air through the load of clothing in the shell ID. A bulb l8 and a portion of a capillary tubing 20 of a liquid type thermostat are shown as located within the shell l0 where response to temperatures therein caused by the heat of the main burner l2 can be obtained. The capillary tubing 20 is connected at the opposite end to an actuating element 22 of the thermostat which is located within the housing 24 of a switching mechanism designated generally by the reference numeral 26.

The main burner I2 is connected to one end of a main fuel supply pipe 28, the opposite end of which is connected to a control device designated generally by the reference numeral 30. An inlet 32 for fuel is provided at the opposite end of the control device 30 from the pipe 28. The inlet 32 communicates with a tapered seat 34 for a tapered plug member 36 of a main fuel cock 3! having a stem 38 projecting exteriorly from the control device 30. A port 40 is formed transversely in the plug member 36 for movement into and out of registry at one end with the inlet 32 as the cock 3'! is rotated between open and closed positions. At its opposite end the port 40 communicates with a passage 42 in the control device 30 when the fuel cock 3! is in open position. The passage 42 communicates with a chamber 44 formed in the control device 30 adjacent the connection of the main fuel pipe 28 therewith.

The chamber 44 is provided with an apertured partition 46 having an annular valve seat 48 formed thereon. A safety valve member 50 is reciprocal in o and out of engagement with the seat 48 for opening and closing a passage 52 which connects the chamber 44 with the con nected end of, th main fuel pipe 28 by way of the apertured partition 46. The valve member 50 is provided with a stem 56 slidably mounted in a projection 58 on the wall of the control device 30 and is biased away from the seat 48 by a coil spring 54 supported on the stem 56 and operable between the valve member 50 and the projection 58.

The pilot burner is supplied with fuel from the inlet 32 of the control device 30 by way of an aperture 60 which is adapted to communicate with an arcuate recess 62 formed in the larger end of the tapered plug member 36 when the cock 3'! is rotated from Ofi" position. The recess 62 also communicates at all times with a passage 64 in the control device 30, the opposite end of which communicates with a pilot valve chamber 66. A pilot valve member 6 8 controls the flow of fuel from the pilot chamber 66 to a connection 10 for the pilot burner l4. The pilot valve member 68 is biased away from its seat by a coil spring 72 operative between the pilot valve member 68 and the bottom Wall of the pilot chamber 66.

The plug member 36 of the main fuel cock 3'! is rotatable in its seat 34 by means of a handle 14 secured to the outer end of the stem 38 and having the usual indicia for the On, Pilot and Off positions (not shown) of the cock 3! displayed thereon. As is customary, fuel can be supplied to the pilot burner M in the pilot position of the main fuel cock by way of passage 60, recess 62 and passage 64 if pilot valve 68 is open, but at such time the port 40 is out of registry with the inlet 32 so that no fuel is supplied to the main burner I2. In the On position the port 48 is in registry with the inlet 32 and the passage 42 so that if valve 58 is open fuel is supplied to the main burner I2 simultaneously with the supply of fuel to the pilot burner I4 due to the arcuate recess 62 maintaining registry with the pilot passages 68 and 64. In the Off position both the port 48 and the arcuate recess 62 are out of registry with their respective inlet passages 32 and 68 and the fuel supply to both the main burner I2 and the pilot burner I4 is prevented.

Thermoelectric safety means are associated with the pilot burner I4 and are responsive to the flame thereof for causing the safety valve 58 to move to closed position in the absence of such flame. This thermoelectric safety means comprises a thermocouple 16 located in proximity of the flame at the pilot burner I4 and having its 'leads connected to a winding 18 carried on a frame 88 of an electromagnet. An armature 82 is engageable with the pole faces of the magnet frame 88 when in attracted position and is spaced therefrom in released position. The electromagnet is provided with a housing 83 supported in the control device 38 between the cock 31 and the pilot valve 68. It will be understood that the current generated by the thermocouple 16 when heated by the flame of the pilot burner I4 is insufficient to attract the armature 82 into engagement with the pole faces of the magnet 88 but is suflicient to maintain such relation when the armature has been placed in attracted position.

Manually operable means are, therefore, pro vided for resetting the armature 82 from its released to its attracted position and comprise a stem 84 for the armature 82 projecting exteriorly from the control device 38 and having a spring 86 carried thereon and operative at one end against a collar on the stem 84. A pushbutton 88 is carried on a lever 98 which is supported upon a reset stem 92 reciprocable in axial alignment with the armature stem 84. The reset stem 92 is supported in a bracket 94 carried by the control device 38 and having a flanged end 96 secured to the control device 38 and forming a closure for the magnet housing 83 and an abutment for the opposite end of the spring 86. The armature 82 is thus biased to its released position and manual pressure applied to the button 88 is required to place the armature in its attracted position. The reset stem 92 is provided with a collar 98 which forms an abutment for one end of a coil spring I88 carried on the reset stem 92 and having its opposite end engaging a projection I82 formed, on the bracket 94. The coil spring I88 serves to bias the reset stem 92 away from the stem 84 and such action is limited by engagement of the collar 98 with an end portion I84 of the bracket 94.

Interposed between the end of the armature stem 84 and the reset stem 92 is one free end of a bell-crank lever I86 having a projection I88 thereon located in the .path of movement of the pilot valve stem 69. The opposite free end II8 of the lever I86 extends substantially normal to the projection I88 and toward the lever 98. The lever I86 is pivotally mounted on a bracket II2 depending from the housing 24 of the switch device 26.

In addition to the support provided by the stem 92 the lever 98 is also supported upon a stem II4 having an inner stem I I6 located within the housing 24. Stem II 4 extends substantially parallel with the stem 92 but is spaced 4 therefrom with the lever 98 extending therebetween. A headed bushing II8 carried on one side of the housing 24 provides a bearing for slidable movement of the projecting end of the stem II 4 and also provides an abutment for one end of a coil spring I28. The opposite end of the spring I28 engages a collar I22 secured to the projecting end of the stem H4 and the arrangement serves to bias the stem II4 outwardly of the housing 24. Such movement of the stem II 4 is limited by a collar I24 which connects the stems H6 and H4 and engages with the head of the bushing H8.

An operating stem I26 extends from adjacent the inner stem II6 through the side of the housing 24 opposite the bushing I I8.

The stem I26 projects into the chamber 44 of the control device 38 and engages with one end of a lever I28 having its opposite end overlying the safety valve member 58. A coil spring I38 is operative between the overlying end of the lever I 28 and a cover I3I for the chamber 44 secured to the control device 38. The spring I38 serves to overcome the bias of the spring 54 for maintaining the safety valve member 58 in engagement with the seat 48. The lever I 28 is pivoted intermediate its ends on a bracket I32 projecting from the control device 38 into the chamber 44 and is operable clockwise for overcoming the bias of the spring I38 to permit the safety valve 58 to be opened.

The manual operating means comprising pushbutton 88 and lever 98 for causing the safety valve 58 to move to open position through the linkage described is prevented from performing this function at all times except when the plug member 36 of the main fuel cock 31 is in the pilot position. Suitable interlocking means between the lever 98 and the main fuel cook 31 are provided and take the form of an angular arm I34 depending from the lever 98 at the junction of the reset stem 92 and which overlies an annular flange I36 formed on the handle 14 and having a slot I38 in its outer edge. The angular arm I34 is normally held in abutting relation with the face of the flange I36 by the bias of the coil spring I28 which tends to urge.

the lever 98 away from the housing 24 and to rotate the angular arm I34 in a clockwise direction about the stem 92 as a fulcrum. In the pilot position of the main fuel cock 31, as indicated on the dial 14, the slot I38 is aligned with the arm I34 and pressure on the button 88 will serve to project the arm I34 into the slot I38 which is designed to receive it.

Electric ignition is provided in this invention and takes the form of an igniter I33 coiled from suitable resistance wire and located in lighting proximity of the pilot burner I4. A switch I35 controls the energization of the igniter I 33 and has a pair of contacts I31 normally spaced from each other by insulation but being adapted to be closed by movement of a flexible 'arm I4I upon which one such contact is mounted. The contacts I31 are suitably mounted on an extension I 43 of the bracket 94 and are operable to closed position by a pin I45 reciprocable in a bearing I41 on the extension I43. The pin H5 is biased away from the contacts I31 by a coil spring I49 extending between the end face of the bearing I41 and an abutment on the pin I45. The terminal end of the pin I 45 is located in operative relation with the arm I34 which is thus adapted to cause closure of the contacts I31 in its projected position.

The housing 24 is connected to the control device 30 by a support I39 extending therebetween. The switching mechanism 26 includes a, main switching means in the form of a switch lever I40 which is pivoted at one end on a bracket I42 carried internally of the housing 24. As shown schematically in the drawing, the switch lever I40 carries on its free end a contact element I44 which is biased into engagement with a relatively fixed contact element I46 by means of a coil spring I48 which is operative between the housing 24 and the switch lever I40 intermediate the pivoted and free ends thereof. The contact element I46 is carried on one side of a terminal bar I50 which projects through a block I52 of insulating material forming a closure for the open end of the housing 24.

The switch lever I40 is restrained against movement under bias of the spring I48 by a lever I54 which is pivoted intermediate its ends on the bracket I42 and has an angular end portion I56 engageable with the switch lever I48 intermediate the coil spring I48 and the contact I44. The opposite end of the lever I54 extends between and is engaged by the opposing ends of the stems H6 and I26 for transmitting motion of the stem II4 to the stem I26. A coil spring I60 carried on the stem I26 is operative between the wall of the housing 24 and the lever I54' to bias the latter so that the angular end I56 is normally 7 in contact with the switch lever I40.

An aperture I58 provided in the lever I54 is adapted for the reception of one end I6I of a latching element I62 which is pivotally mounted intermediate its ends in the housing 24 and extends substantially parallel with the stem H6 which overlies it. A coil spring I64 is operative between the base of the housing 24 and the end of the latching element I62 on the side of the pivotal mounting therefor opposite the end I6I.

. The spring I64 serves to rotate the latching element I62 in a counter-clockwise direction so that when the parts are in the position shown in the drawing, the end I6I engages the wall of the aperture I58 in the lever I54. However, when the lever I54 is rotated clockwise on its pivotal mounting a, step portion I66 on the end I6I of the latching element I62 will then engage the wall of the aperture I58 to prevent counterclockwise movement of the lever I54. The lever I 54 is then in its latched position.

The latching operation described may be-prevented by operation of a slidable pin I68 which may be held in engagement with the underside of the latching element I62 intermediate its pivotal mounting and the end I6I by the arm IIO of the lever I06. The slidable pin I68 is biased away from the latching element I62 by a coil spring I10 operative between the housing 24 and a collar I12 formed on the pin I68 exterior of the housing. It is apparent, therefore, that the latching operation described can only be effected when the arm H is moved to the broken line position shown on the drawing, such movement occurring when the lever I06 is rotated clockwise to the broken line position shown on the drawing.

Auxiliary switching means is provided for cooperation with terminal bar I50 and takes the form of a switch lever I14 positioned on the opposite side thereof to the switch lever I40. A contact I16 on the lever I14 is adapted to engage a contact I18 carried on the terminal bar I50. The switch lever L14 is, however, adapted for snap action into and out of contact engaging position. To this end, the conventional lever and spring device is employed comprising an operating lever I and an overcenter spring I82. The spring I82 has one end hooked around a suitably formed bearing portion on the switch lever I14 and its opposite end hooked around a similar bearing on the operating lever I80. The switch lever I14 has a pair of legs I84, only one of which is shown in the drawing, having the terminal end of each leg I84 formed with a knife-edge portion for cooperation with a knife-edge bearing I86 formed in a bracket I88 carried internally of the housing 24 on one side of the bracket I42. Likewise, the end of the operating lever I80 opposite the bearing for spring I82 is also formed with a knife-edge portion for cooperation with a knife-edge bearing I90 formed in a, bracket I92 carried internally of the housing 24 on the opposite side of the bracket I42.

The end of the operating lever I80 opposite the knife-edge bearing I90 extends beyond the stem H6 and is suitably apertured to provide clearance therefor. This depending end of the operating lever I80 extends adjacent an inclined portion I63 formed on the latching element I82 and which it is adapted to engage upon sufficient movement of the lever I 80 in a clockwise direction.

The operating lever I80 is adapted to be engaged by a stud portion I93 carried by the actuating element 22 of the temperature responsive device and will consequently be moved thereby upon expansive and contractive move ment of the element 22. The studl93 is also adjustable, together with the actuating element 22, with respect to the operating lever I60 by a manual adjusting means in the form of a dial I94 having the usual temperature indicia (not shown) thereon. As shown schematically in the drawing, the dial I94 is carried on a threaded stem I96 which engages the wall of the housing 24 and is suitably apertured to receive in slidable engagement therewith a connecting pin I98 carried by the actuating element 22. The arrangement is such that upon rotation of the dial I 94 the actuating element 22 and stud I93 will move axially into and out of operative engagement with the operating lever I80 to set the temperature at which the switching means 26 will operate.

As shown schematically in the drawing, the electric motor I6 is controlled through the switching mechanism 26 by having one terminal thereof connected to one line wire 200 and the opposite terminal connected by wire 202 to the terminal bar I50, the other line wire 204 being connected by wire 206 to contact I44 and to contact I46 by wire 208.

The circuit for the igniter I33 may be traced from line wire 200, wire 201, contact pair I31, wire 209, one terminal of the primary coil of a step-down transformer 2H, and by wire 2I3 from the opposite terminal of the primary of transformer 2| I to the line wire 204. The igniter I33 has its opposite ends connected to opposite terminals of the secondary coil of transformer 2H and is consequently energized whenever the contact pair I31, controlling the circuit of the primary of transformer 2| I, is closed.

In order to prevent manual operation to open the safety valve 50 before the armature 82 is engaged with the magnet 80, suitable interlocking means are employed. This means takes the form of a slidable pin 2 I 0 which projects through 75 the base of the housing 24 substantially parallel with the other slidable pin I68. In this instance, the slidable pin 2I0 projects into the path of movement of the collar I24 on the pin H6 and is held in such position by engagement with the arm IIO of the lever I06. The slidable pin 2I0 is, however, biased from such position by a coil spring 2I2 operative between the base of the housing 24 and a collar 2I4 carried on the pin 2I0 exteriorly of the housing 24. Thus, when the arm H is in the broken line position shown in the drawing, the bias of the spring 2I2 will serve to move the pin 2I0 out of the path of movement of the collar I24.

Means are provided to prevent opening of the safety valve 50 and closing of the contacts I44, I46, to initiate operation of the motor I6 unless the dial I94 of the temperature responsive means is moved from Off to a desired temperature setting. This means includes a cam element 2I6 carried by the dial I94 and having a shoulder 2I8 thereon. A bar 220 extends from the cam portion 2I6 through the housing 24 into engagement with the switch lever I40. When the dial is in Off position, the bar 220 is positioned against the shoulder 2I8 as shown in the drawing. The bar 220 carries a wedge-shaped element 222 located intermediate the switch levers I40 and I14 and which is movable with the bar 220 transversely of these switch levers. Cooperating with the wedgeshaped element 22 is a slidable pin 224 which engages the element 222 at one end and extends substantially normal to the bar 220 through the base of the housing 24 to the exterior thereof. The exterior end of the pin 224 engages one free end of a member 226 which is pivoted on the base of the housing 24 and has its opposite end engaging the underside of the collar I12 on the pin I68. Thus, upon transverse movement of the bar 220 relative to the switch levers I40 and I14, the wedge-shaped element 222 will move across the end of the slidable pin 224 causing axial movement thereof which serves to rotate the pivoted element 226 in a clockwise direction. The pivoted element 226 thus moves the pin I68 axially in the opposite direction to pin 224 and against the bias of the spring I associated therewith.

Means for guarding against the hazards of overtemperature in the appliance take the form of a thermally responsive device of the fusible material type. In this embodiment, the stepped portion I66 of the latching element I62 extends beyond the adjacent wall of the housing 24 and terminates short of the opposite wall of the control device 30. A lever 228 extends substantially parallel with the latching element I62 across the control device and is pivotally mounted, as at 229, on the said opposite wall thereof. One free end of the lever 228 is thus adapted to be engaged by the extended end of the stepped portion I66 for rotation of the lever 228 but is normally maintained out of such engagement by means to be described.

The opposite free end of the lever 228 extends beyond the control device 3|] and is supported between a pair of tension springs 230, 232. The spring 232 is stronger than the spring 230 and is attached through a link of fusible material 234 to a stationary part of the appliance. The spring 230 is attached directly to a similar stationary part. The fusible link 234 is subject to the temperature of the jacket (not shown) of the appliance and is designed to melt at a predetermined temperature.

In the operation of the device, the handle 14 is turned to the pilot position to align the slot I38 with'the angular arm I34 of the lever 90. In this position of the main gas cook 31 the plug member 36 thereof will permit flow of fuel from the inlet 32, passage 60, arcuate recess 62 and passage 64 to the pilot valve chamber 66. The push-button 88 is then operated to project the angular arm I34 through the slot I38 and move the stem 92 against the bias of the spring I00 to the left, as viewed in the drawing. Such movement of the stem 92 is due to the clockwise movement of the lever about the stem II4 as a fulcrum. It will be apparent that the engagement of the collar I24 on the stem II6 with the slidable pin 2I0 prevents any movement of the stem II 6 at this time. Thus, the movement of the stem 92 causes the lever I06 carrying the arm IIO to move in a clockwise direction to the broken line position shown in the drawing. In this position the pilot valve 68 is moved away from its seat under bias of the pilot valve spring 12 so that fuel may flow by way of the connection 10 to the pilot burner I4. At the same time, the armature stem spring 86 is compressed by the clockwise movement of the lever I06 and the armature 82 is placed in attracted position relative to the pole faces of the magnet 80.

The inward movement of the arm I 34 serves to operatively engage it with the pin I45 and overcome the bias of the spring I49. The resulting closure of thecontact'pair I 31 serves to energize the igniter I33 through the described circuit. 3

The fuel flowing from pilot burner I4 is then ignited and the heat of the flame thereof will cause the thermocouple 16 to generate suflicient current to energize the coil 18 and retain the armature 82 in its attracted position. However, should the pilot burner fail to produce a flame or should the current generated in the thermocouple 16 for some other reason be insufiicient for the purposes described, then the coil spring 86 being stronger than the spring 12, will cause the lever I06 to be returned to its full line position shown in the drawing, and the pilot valve 68 will consequently be closed. Hence, it is necessary to continue pressure on the push-button 88 at least until the current in the thermocouple 16 is 'sufficient to keep the armature 82 in the attracted position. The bias of the spring 2l2 causes the pin 2I0 to be moved out of the path of the collar I24 on stem H6 and the fulcrum e point of the lever 90 no longer exists at this point.

After the armature 82 is thus held in attracted relation with the pole faces of the magnet 80, the push-button 88 is further operated, but at this time the lever 90 rotates counter-clockwise about the stem 92 as a fulcrum due to this stem being prevented from further movement to the left as viewed in the drawing after the armature 62 is reset. Thus, the stem II6 moves to the left, as viewed in the drawing, and causes the lever I54 to move clockwise on its pivotal mounting and the pin I26 to move to the left causing the lever I28 to move clockwise. The bias of the spring I30 is thus overcome to permit the safety valve 50 to open under bias of the spring 54. However, although the lever I54 is moved away from the switch lever I40 at this time, there can be no engagement between the contacts I44 and I46 due to the bar 220 associated with the dial I94 engaging the switch 9 lever I40 and maintaining it in its normally open contact position. Moreover, there is no flow of fuel to the main burner I2 when the safety valve 50 is opened due to the main fuel cook 31 being still in the pilot position.

Upon release of manual pressure on the pushbutton 88, arm I34 moves to the right as viewed in the drawing and the igniter circuit is broken at the switch I35. At this time, the lever I54 will return to its original position unless the dial I34 of the temperature responsive device is rotated from the Oil position to a selected temperature setting. When the dial I94 remains in the Off position as shown in the drawing then the bar 220 is held in the position shown in the drawing and the wedge-shaped element 222 maintains the slidable pin 224 in position to retain the pivoted element 226 against the collar I12 of the pin I68 under bias of its spring I10. As the pin I68 is then engaged with the underside of the latching element I62, there can be no pivotal movement of the latching element to effect engagement between the stepped portion I66 thereof with the lever I54 regardless of the clockwise movement of the latter. This arrangement provides a convenient "Olf position of the device from the temperature responsive device.

When the dial I94 is rotated to a selected temperature setting the cam element 2I6 thereon will cause the bar 220 to move to the right as viewed-in the drawing and release the slidable pin 224 for axial movement. Thus, under bias of the spring I the slidable pin I68 will now move axially away from the underside of the latching element I62 which rotates on its pivot to latching engagement with the lever I54. Moreover, the movement of the bar 220v to the right permits the switch lever- I40 to be rotated clockwise by the spring I 48 into position where the contacts I44, I46 are engaged. A circuit for the motor I6 is completed from line wire 200, motor I6, wire 202, terminal bar I50, contact I46, I44, wire 206 and line wire 204. However, although the motor I6 is now energized to drive the drum and the fan or blower, there is as yet no fuel flow past the open safety valve 50. This is, of course, due to the main fuel cock being still in the pilot position. The handle 14 of the main fuel cook 31 is now rotated to align the port 40 in the plug member 36 with the inlet 32 so that fuel can flow by way of passage 42, chamber 44 and outlet 52 to the main burner I2 where it is ignited by the flame at the pilot burner I4. Thus, the control device for the drying apparatus is in full operation.

As the temperature at the bulb I8 increases and the actuating element 22 expands, then the operating lever I80 is rotated by the stud I93 in a clockwise direction about the nife-edge bearing I90. The switch lever I14 will move with snap action into position to engage contacts I16, I18 after the movement of the operating lever I 80 has progressed sufficiently to produce overcenter operation of the spring I82. Either substantially simultaneously with this action on the part of the operating lever I80 or upon a further rise in temperature causing additional clockwise movement of the lever I80, the depending end thereof will ride up the inclined surface I63 of the latching element I62 and will release the stepped portion I66 from engagement with the lever I54. Thus, under bias of the springs I60 and I associated with the lever I54 and the safety valve 50, respectively, the lever I54 is moved in counter-clockwise direction to open the 10 contacts I44, I46 at approximately the same time that the safety valve 50 is closed.

Fuel flow to the main burner I2 is now cut-off but the motor I6 continues to run since engagement between contacts I16 and I18 of the auxiliary switching means still exists. The circuit for the motor I6 is established from line wire 200, motor I6, wire 202, terminal bar I50, contacts 118, I16, wire 208 and line wire 204. When the temperature at the bulb drops in amount corresponding to the diiferential of the thermostat, then the actuating element 22 contracts sufllciently to cause overcenter snap-action of the auxiliary switch means in the opposite direction. The engagement between contacts I16, I18 is thereupon broken and the motor l6 ceases to run.

If a new batch of material to be dried is placed in the appliance it will only be necessary to operate the push-button 88 and the mechanism returns to operating position because the lever I54 will be rotated clockwise by means of the pin I I6 and the latching element I62 will lock it in the operating position. Pin I26, in turn, keeps the safety valve 50 in open position and fuel is again admitted to the main burner I2. In the event that the appliance has to be stopped in the drying operation, it is only necessary to rotate the dial I 94 to the Oif position. In this operation, the bar 220 is moved to the left as viewed in the drawing and through the described arrangement of the wedge-shaped element 222, pin 224, pivoted element 226 and pin I68, the latching element will be released and the lever I54 returned to its original position. Hence, engagement between the contacts I44 and I46 ceases and safety valve 50 is closed as previously described. It will be observed that during this operation the main fuel cook 31 remains in position with the plug member 36 having the port 40 in registry with the inlet 32 and the passage 42. At the time that the main fuel cook 31 is in this position the pilot burner I4 is receiving fuel and remains lighted. Thus, inorder to extinguish the pilot burner I4 it is necessary to rotate the main fuel cook 31 to the Off position and, after the thermocouple 16 cools, the armature 82 will be released from the pole faces of the magnet 80. The lever I06 is thus rotated counter-clockwise and the pilot valve 68 becomes closed.

If, during the running operation of the control device, the flame of the pilot burner I4 should be extinguished and the thermocouple 16 cease to generate current, then the lever I06 will be returned to its original full-line position as shown in the drawing due to release of the armature 82 from attracted position relative to the pole faces of the magnet 80. Hence, the pin I168 will be moved axially by the arm IIO of the lever I06 and will release the latching element I62 which holds the lever I54 in its tilted or operating position. The valve 50 will close under bias: of the spring I30 and engagement between the contacts I44, I46 will-cease.

If, during a drying operation, the temperature prevailing in the applianceshould reach an undesired high value, then the overtemperature safety tripping device comes into operation. Thus, the fusible link 234 which is subject to such high temperature will melt and release the tension of the sprin 232. Under such conditions, the spring 230 attains full control of the position which the lever 228 occupies and causes rotation thereof in a counter-clockwise direction as viewed in the drawing. An engagement of the adjacent free end of the lever 22:; with the extension of the I latching element I62 thereupon occurs. Such engagement serves to tilt the lat ching element I62 on its pivot and release the lever I54 as in the case of flame failure. In both cases, therefore, the fuel supply is shut-off by closing of the valve 50 and the appliance become cool.

The system of interlocking herein disclosed renders the control device quite safe in use. It will be appreciated that the depending end 134 of the lever 90 can only be moved to the left when the handle 14 of the main fuel cock 3! is in the pilot position. On the other hand, the opposite end of this lever 90 can be moved to the left only after rotation of the lever I06 has caused the arm H carried thereby to move out of the way of the pin 2l0 permitting axial movement thereof. Moreover, the switch lever I 40 can rotate clockwise to engage contact I with contact I46 only after the bar 220 has been moved to the right upon operation of the dial I94 to a selected temperature setting. Hence, it is impossible to start the control device in operation without having the temperature control dial I94 and the handle of the fuel control device 31 in' the proper positions.

The described feature of causing the motor to continue to run and drive the fan and drum after the heating element of the appliance is cut-off adds considerable utility to the device. Thus, when the appliance finally ceases to operate the clothes can then be removed without fear of burning the hands and, at the same time, an additional drying period has been obtained. After the wet clothes are put in the appliance and the controls set as described, then the heating cycle and cooling down period will take place automatically and thereafter the appliance will shut itself down. The control is thus fully automatic after the starting period and will operate safely with no attention on the part of the operator once the controls have been properly set. Moreover, the starting operation is facilitated by the provision for electric ignition by operation of the single reset button. In addition, overtemperature in the appliance cannot create hazardous conditions with the safety features added by this invention.

It will be understood that various changes may be made in the details of construction and arrangement of parts and that the control device may be utilized for useful purposes other than clothes-drying controls. This and other modifications can be made within the scope of the appended claims without departing from the invention defined therein.

We claim:

1. A control apparatus for fuel burners having main and pilot burners, comprising in combination, a control device operable between positions for controlling the supply of fuel to at least the main burner, means for biasing said control device to prevent said fuel supply, actuating means operable for overcoming said biasing means and causing movement of said control device to a fuel supply position, an electric igniter for the pilot burner, means responsive to a flame at the pilot burner for releasing said actuating means in the absence of said flame and causing operation of said control device to said biased position, reset means for operating said actuating means and resetting said flame responsive means for said releasing operation, an initially open switch controlling energization of said igniter and operatively associated with said reset means for operation resetting operation,

to closed position during the and locking means effective upon initial operation of said reset means foractuating means in operative position, and means operably associated with said reset means for rendering said latching element inoperative, said last means being rendered ineffective upon said initial operation of said reset means.

4. A control apparatus for fuel burners having main and pilot burners comprising in combination, a control device operable between positions for controlling the supply of fuel to at least the main burner, means for biasing said control device to prevent said fuel supply, actuating means operable for overcoming said biasing means and causing movement of said control device to a fuel supplying position, a latching element biased to latching position and cooperable with said actuating means for holding the same in operative position, an electric igniter for the pilot burner, means responsive to a flame at the pilot burner for releasing said latching element in the absence of said flame and causing operation of said control device to said biased position, reset means for operating said actuating means and resetting said flame responsive means for said releasing operation, and an initially open switch controlling energization of said igniter and operatively associated with said reset means for operation to closed position during the resetting operation.

5. The combination defined in claim 4 wherein locking means are provided effective upon initial operation of said reset means for holding said actuating means in an inoperative position during the resetting operation.

6. A control apparatus for fuel burners having main and pilot burners, comprising in combination, a control device operable between positions for controlling the supply fuel to at least the main burner, means for biasing said control device to prevent said fuel supply, a lever device operable for overcoming said biasing means, manually movable means for operating said lever device and biased to inoperative position, a latching element biased to latching position and cooperable with said movable means for retaining the same in an operative position, a second lever device operable for overcoming the bias of said latching element and releasing the same out of latching position, an electric igniter for the pilot burner, means responsive to a flame at the pilot burner for rendering said second lever device operable in the absence of said flame and causing operation of said control device to said biased position, second manually movable means for rendering said second lever device inoperative and resetting said flame responsive means for said releasin operation, connecting means between said first and second manually movable means, an initially open switch controlling energization of said igniter and operatively associated with said connecting means for operation to closed osition during the resetting operation, and locking means effective upon initial operation of said connecting means for holding said first manually movable means in an inoperative position during the resetting operation.

7. A control apparatus for fuel burners, comprising in combination, a control device operable between positions for controlling the supply of fuel to be burned, means for biasing said control device to prevent said fuel supply, actuating means operable for overcoming said biasing means and causing movement of said control device to a fuel supply position, a latching element biased to latching engagement with said actuating means and being movable against said bias to a released position, a tripping device movable into operative engagement with said latching element for releasing the same, and means for holding said tripping device out of the path of movement of said latching element during normal operation of said control device between said controlling positions, said last means including an element responsive to an abnormal condition caused by the burning fuel for rendering said holding means inoperative.

8. The combination as defined in claim 7 wherein said tripping device includes a pivoted lever biased into operative engagement with said latching element, and said last means including means for holding said lever against the last said bias out of the path of movement of said latching element including a fusible link which is responsive to an abnormal temperature condition caused by the burning fuel for rendering said holding means inoperative upon occurrence of said abnormal temperature.

9. A control apparatus for fuel burners comprising in combination, a control device operable between positions for controlling the supply of fuel to be burned, means for biasing said control device to prevent said fuel supply, actuating means operable for overcoming said biasing means and causing movement of said control device to a fuel supply position, a latching element biased to latching engagement with said actuating means and being movable against said bias to a released position, means responsive to a condition caused by the burning fuel for releasing said latching element upon occurrence of said condition and causing movement of said control device to said biased position, a tripping device including a pivoted lever biased into operative engagement with said latching element, and means including a fusible link for holding said lever against the last said bias out of the path of movement of said latching element and being responsive to another' said condition caused by the burning fuel for rendering said holding means inoperative and causing movement of said control device to said biased position irrespective of the first said condition.

10. A control apparatus for fuel burners having main and pilot burners comprising in combination, a control device operable between positions for controlling the supply of fuel to at least the main burner, means for biasing said control device to prevent said fuel supply, actuating means operable for overcoming said biasing means and causing movement of said control device to a fuel supply position, a latching element biased to latching engagement with said actuating means and being movable against said bias to a released position, means responsive to extinguishment of a flame at the pilot burner for releasing said latching element for movement of said control device to said biased position, means responsive to a temperature condition caused by operation of the main burner for also releasing said latchin element for movement of said control device to said biased position, a tripping device biased into operative engagement with said latching element, and means for holding said tripping device out of the path of movement of said latching element during operation of said control device by said fiame responsive or said temperature responsive means, said holding means including an element responsive to an abnormal temperature condition caused by operation of the main burner for rendering said holding means inoperative and causing release of said latching element for movement of said control device to said biased osition thereof.

VICTOR WEBER. RUSSEIL F. GARNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,320,696 Knight Nov. 4, 1915 1,842,330 Te Pas Jan. 19, 1932 1,966,735 Sackett July 17, 1934 1,981,012 Wegener Nov. 20, 1934 2,179,638 Jenkins Nov. 14. 1939 

